1. Field of the Invention
The present invention relates to a method for network formation and communication in a Bluetooth group, and more particularly, to a method for Bluetooth on-demand routing and networking formation and a communication method in Bluetooth group ad hoc network capable of minimizing the number of piconets. This present application is based on Korean Patent Application Nos. 2002-22824, 2002-34673, and 2002-72841, filed Apr. 25, 2002, Jun. 20, 2002, and Nov. 21, 2002, respectively, which are incorporated herein by reference.
2. Description of the Prior Art
First, a conventional network formation algorithm for a Bluetooth network will be described.
Salonidis has suggested a Bluetooth topology construction protocol (BTCP) for scatternet formation. According to the BTCP, there are three stages. In the first stage, a coordinator possessing information about all nodes is selected using a state-changing technique for symmetric link formation. In the second stage, the selected coordinator decides the functions of the respective nodes. Then the practical connection is made in the third stage. The BTCP is based on the condition that all the nodes are within radio range.
Based on the above condition, and also based on all the defined nodes, Aggarwal et al. have grouped the network into independent piconet clusters. When a so-called “super-master” that has the information about all the nodes is selected, the re-construction of, and connection between the piconets is performed under the monitor, or control of this super leader.
Law et al. have suggested a one-step scatternet formation algorithm that has O(log n) times of complexity and O(n) message complexity. According to this, all the nodes are separated to have only one leader. The constituent is a group of nodes that are connected to one another. The leader enters “seek and scan” state, and then selectively performs processes such as “connection”, “merge”, “mitigate” or moving of devices. The drawback of Law et al. lies in the limitation that requires all the nodes to be within communication range.
In the blue-tree algorithm, a node needs to have information as to whether it is a root node or not, and information about one-hop peripherals thereof.
Tan et al. simplified packet routing and scheduling by providing routes and loop free paths, respectively. In the tree style structure, however, due to the fact that the joint node serving as master in one piconet would serve as slave in the other, two piconets tend to be closely related to each other.
Also, all the above algorithms focus the formation of scatternet on an individual operation in the data link layer, not taking actual traffic conditions and traffic requests into account. Problematically enough, “active” state has to be resumed periodically, during, or after, the initial scatternet formation even when there is little traffic, to make sure that the point-to-point link is connected in the entire scatternet at the level of the physical link.
In other words, power, which is a very essential factor of wireless communication devices, is unnecessarily consumed to maintain the links. Addressing such problems, Raman et al. suggested a theory on layer optimization of scatternet link formation with on-demand routing. However, more detailed analysis and realization thereof have yet to come.
Bhagwat and Segall suggested a routing vector method that routes the packet traffic in the scatternet. Liu Y used network formation using newly defined LMP command language. But as found in the simulation test, traffic waiting time is considerably prolonged due to many inquiries in Bluetooth.